DNA mismatch repair (MMR) protein immunohistchemistry of hereditary non-polyposis colorectal cancer (HNPCC) related tumors and genetic analysis of MMR gene mutations.

Interventions: IHC of MMR proteins, genetic or epigenetic analyses of MMR genes Primary outcome(s): Screening of HNPCC related tumors by IHC for loss of MMR protein expression and observation of the clinical features assciated with MMR deficiency. Study Design: Single arm Non-randomized